Spinning viscose



-Patented Feb. 16, 1926.

UNITED STATES PATENT OFFICE.

SPINNING VISCOSE.

'No Drawing.

To all whom it may concern:

Be it known that I, JACQUES COENRAAD HARTOGS, a subject of the Queen of the Netherlands, residing at Arnhem, Province of Guelderland, Kingdom of the Netherlands, have invented certain new and useful Improvements in Spinning Viscose, of which the following is a specification.

In the art of spinning threads of viscose it is usual to employ spinning baths containing acid by which the viscose is not only coagulated but alsoldecomposed. One of t e products of this decomposition is H S. Owing to the rather high tem erature of the spinning bath all the H S oes not remain in solution, a lar e portion escaping in gaseous condition. T is evolution of gas not only leads to formation of gas-bubbles within the thread, unfavourably affecting its strength and elasticity but also becomes a nuisance because the toxicity of H 8 makes it necessary to protect the operators and the environments, which is not im ossible, but requires complicated and cost y processes and apparatus.

It is an object of this invention to eliminate the, ill-effects of the sulphureted hy drogen in a manner which does not require complications, considerable expense or a more complicated after-treatment of the 5 un silk. According to the invention this ob ect is attained by the use of a spinning bath containing one or more ferric salts such as ferric sulphate. The ferric salts may be added to the spinnin bath or a ferric com ound may be added w ich forms the desire ferric salt I with the acid of the spinning bath.

oxidizing agents but none ofthese agents conforms with all the requirements. Thus permanganate deposits manganese dioxide which requires an after-treatment with bisulphite or the like. Other oxidizing agents act too strongly and attack the cellulose, some others attack the spinning ducts and accessories and many are impracticable owingT to their high price.

erric salts, especially ferric sulphate, have none of these drawbacks.

In this case the ferric salt cannot be regarded as an oxidizing agent and is more com arable with CuSO, and the like, which" com ine with H S. These latter,

however, .form insoluble sulphides,

which would have Application filed June so, 1924. Serial No. 723,364.

a detrimental effect. The ferric salt, however, in consequence of the instability of ferric sulphide and the solubility of ferrous sulphide in acids, only yields sulphur and a ferrous salt. It is true that the precipitated sulphur is insoluble, but by its rather low specific gravity its very finely divided state and the fact that it deposits for the major part on the thread and so protects it and because it may be removed entirely afterwards, this sulphur precipitate is an advantage.

It is well-known that finely subdivided sulphur prevents the newly spun threads from adhering toeach other and therefore protects the thread from breaking in the twining process.

Ferric salts, such as ferric sulphate as well as the ferrous salts produced may be washed out easily and completely and the oxidizing properties of ferric salts are so extremely weak that there can be no question of attack of the cellulose.

Ferrous salts, especially ferrous sulphate, are easily reoxidized by electrolytic oxidation to ferric salts, which makes it possible to regenerate the spinning bath and to maintain a concentration of ferric salts of any desired degree without being obliged to filter the spinning bath or to renew it or reinforce it more than is the case at present.

Ferrous salts, especially ferrous sulphate, have still another valuable property, which they sharewith zinc sulphate, namely the property of preventing the threads from adhering together and. of increasing their lustre. Said property is well-known for zinc-sulphate but is not yet explained. It is true that H S may be also removed by It is remarkable that by the use of ferric salts the spinning bath is kept absolute] odourless; it seems as if the products whic give CS its bad odour such as mercaptans,

are made harmless. By the said properties ferric salts are entitled to a quite unique po- 7 sition and cannot be compared with any known means for obtaimng the samet results. Theconcentration of ferric-salts required to remove quickly all H S need be only,

2. In the process of spinning viscose, the An acid spinning bath for viscose constep which consists in adding ferric snltaming ferric sulphate in addition to the phate to an acid spinning bath to prevent usual constituents. 10

\ evolution of sulphureted hydrogen. In testimony whereof I afiix my signa- 5 3. An acid spinning bath for viscose conture.

taining a ferric salt in addition to the usual constituents. JACQUES COENRAAD HARTOGS. 

